In related art, various microwave processing apparatuses of this type have been proposed for uniform heating of a portion to be heated. Regarding multiple power feeding, a radio-frequency heating apparatus has been proposed, in which the mode of a microwave generated by a magnetron is continuously changed by alternately closing two power feeding ports by sliding means formed of a solenoid or the like (for example, see Patent Document 1).
Moreover, regarding a cavity wall surface, a radio-frequency heating apparatus has been proposed, in which an uneven portion for reducing a contact area between an object to be heated and a bottom surface is formed (for example, see Patent Document 2).